Without knowledge, critical thinking — or critical reading, or critical writing, or critical speaking, or critical listening — probably isn't all that critical or all that good. Consider:
- Without geographic knowledge — the regions of the world, the world's major physical features and political borders — and chronological knowledge — basic periodization schemes and accompanying dates — there can be no quick comprehension of a given world history text.
- Without numbers knowledge — integers, fractions, percentages, decimals, multiples, factors, squares — there can be no fluid, critical thinking in secondary mathematics.
- Without knowledge of genetics — chloroplasts, mitochondria, sex-linked genes, phenotypes, genotypes — there can be no “explanation of how the inheritance pattern of many traits cannot be accounted for by Mendelian genetics.” 
- Without language knowledge — mechanics, vocabulary, conventions — there can be no fluent engagement in wide and critical reading and writing.
The best courses, teachers, and curricula emphasize both the development of knowledge and the use of that knowledge in critical thinking.
If you're knowledge-lite, start by:
- Determining what knowledge is essential to your course
- Organizing that knowledge into a coherent, manageable whole (the AP Course and Exam Descriptions are exceedingly helpful with both this item and the previous one)
- Using frequent, low-stakes quizzing to help students remember and recall information (see Erica Beaton's great Make It Stick post)
If you're critical thinking-lite, start by:
- Developing a debatable question that a knowledge-rich unit could conceivably answer
- Holding a pop-up debate to explore that question at the end of the knowledge-rich unit
- Tracking the holes in student argumentative ability that the pop-up debate brings to light and then teaching to fill those holes for the rest of the school year in the context of further end-of-unit pop-up debates
Certainly no silver bullets here, but a start.
- Taken from Learning Objective 3.16 and Scientific Practice 6.3 in the AP Biology Course and Exam Description.